This invention relates to the stabilization of fats and oils against oxidative degradation. More particularly, a fat containing unsaturation stabilized by a diarylamine substituted triazine compound.
A wide variety of naturally occurring oils and fats contain a mixture of olefinic compounds which vary in unsaturation and hence oxidizability from the singly unsaturated oleic to the polyconjugated eleostearic esters. Oxidation is the major cause of deterioration of edible oils and fats. Oxidative deterioration of domestic fats such as butter, margarine, lard and cooking oils and the foodstuffs into which they are incorporated, is manifested initially as loss of flavor. This is followed by rancidity due to the formation of aldehydes and acids which become increasingly toxic. Long before this state is reached, however, important minor constituents of the natural oils and fats such as the vitamins and some of the terpenoid flavoring constituents have been destroyed. Protection against the onset of rancidity is an ongoing desired objective in the food processing industry.
Aldehydes have been recognized for many years as the chemical agents responsible for rancidity. These products have been shown to be derived from initially formed hydroperoxide. The primary initial products of the autoxidation of fatty acid esters, the hydroperoxides, appear to be odorless and flavorless. However, a host of carbonyl compounds, acids, and other products are formed, through decomposition and further oxidation of the hydroperoxides. Many of the secondary products have relatively low molecular weights, and presumably all such compounds contribute to the off-flavors and odors.
Perhaps the principal objection, in many parts of the world, to rancidity in fat products has been an esthetic aversion to the rancid odor and flavor. People who become accustomed to the natural flavor and odor of fresh and carefully processed food materials acquire a distaste for any flavor and odor that can be associated with poor processing or long storage under unfavorable conditions.
A second, and fundamentally more important, basis for objecting to common oxidative rancidity is based on possible harmful effects that result from the consumption of oxidized fat. The extent to which rancid fat should be considered harmful continues to be a controversial question.
It may be said unequivocally that oxidized fats cause some destruction of certain fat-soluble vitamins and possibly other nutrients in the diet. In particular, it has been demonstrated that several fat-soluble vitamins and carotene are destroyed in oxidized fats.
Of the more efficient synthetic antioxidants which have been extensively tested in foodstuffs, the most important are mixed 2 and 5 tert.-butyl-4-methoxy phenols (BHA) and 2,5-di-tert.-butyl-4-methylphenol and a number of other antioxidants, including bis-phenols, amine antioxidants such as diphenyl-p-phenylene-diamine (DPPD) and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline.